util/Collection/IteratorMicroBenchmark.java

/*
 * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @summary micro-benchmark correctness mode
 * @run main IteratorMicroBenchmark iterations=1 size=8 warmup=0
 */

import static java.util.stream.Collectors.summingInt;
import static java.util.stream.Collectors.toList;

import java.lang.ref.WeakReference;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.PriorityQueue;
import java.util.Spliterator;
import java.util.Vector;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.LinkedTransferQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.LongAdder;
import java.util.regex.Pattern;

/**
 * Usage: [iterations=N] [size=N] [filter=REGEXP] [warmup=SECONDS]
 *
 * To run this in micro-benchmark mode, simply run as a normal java program.
 * Be patient; this program runs for a very long time.
 * For faster runs, restrict execution using command line args.
 *
 * This is an interface based version of ArrayList/IteratorMicroBenchmark
 *
 * @author Martin Buchholz
 */
public class IteratorMicroBenchmark {
    abstract static class Job {
        private final String name;
        public Job(String name) { this.name = name; }
        public String name() { return name; }
        public abstract void work() throws Throwable;
    }

    final int iterations;
    final int size;             // number of elements in collections
    final double warmupSeconds;
    final long warmupNanos;
    final Pattern filter;       // select subset of Jobs to run
    final boolean reverse;      // reverse order of Jobs
    final boolean shuffle;      // randomize order of Jobs

    IteratorMicroBenchmark(String[] args) {
        iterations    = intArg(args, "iterations", 10_000);
        size          = intArg(args, "size", 1000);
        warmupSeconds = doubleArg(args, "warmup", 7.0);
        filter        = patternArg(args, "filter");
        reverse       = booleanArg(args, "reverse");
        shuffle       = booleanArg(args, "shuffle");

        warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
    }

    // --------------- GC finalization infrastructure ---------------

    /** No guarantees, but effective in practice. */
    static void forceFullGc() {
        CountDownLatch finalizeDone = new CountDownLatch(1);
        WeakReference<?> ref = new WeakReference<Object>(new Object() {
            protected void finalize() { finalizeDone.countDown(); }});
        try {
            for (int i = 0; i < 10; i++) {
                System.gc();
                if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
                    System.runFinalization(); // try to pick up stragglers
                    return;
                }
            }
        } catch (InterruptedException unexpected) {
            throw new AssertionError("unexpected InterruptedException");
        }
        throw new AssertionError("failed to do a \"full\" gc");
    }

    /**
     * Runs each job for long enough that all the runtime compilers
     * have had plenty of time to warm up, i.e. get around to
     * compiling everything worth compiling.
     * Returns array of average times per job per run.
     */
    long[] time0(List<Job> jobs) throws Throwable {
        final int size = jobs.size();
        long[] nanoss = new long[size];
        for (int i = 0; i < size; i++) {
            if (warmupNanos > 0) forceFullGc();
            Job job = jobs.get(i);
            long totalTime;
            int runs = 0;
            long startTime = System.nanoTime();
            do { job.work(); runs++; }
            while ((totalTime = System.nanoTime() - startTime) < warmupNanos);
            nanoss[i] = totalTime/runs;
        }
        return nanoss;
    }

    void time(List<Job> jobs) throws Throwable {
        if (warmupNanos > 0) time0(jobs); // Warm up run
        final int size = jobs.size();
        final long[] nanoss = time0(jobs); // Real timing run
        final long[] milliss = new long[size];
        final double[] ratios = new double[size];

        final String nameHeader   = "Method";
        final String millisHeader = "Millis";
        final String ratioHeader  = "Ratio";

        int nameWidth   = nameHeader.length();
        int millisWidth = millisHeader.length();
        int ratioWidth  = ratioHeader.length();

        for (int i = 0; i < size; i++) {
            nameWidth = Math.max(nameWidth, jobs.get(i).name().length());

            milliss[i] = nanoss[i]/(1000L * 1000L);
            millisWidth = Math.max(millisWidth,
                                   String.format("%d", milliss[i]).length());

            ratios[i] = (double) nanoss[i] / (double) nanoss[0];
            ratioWidth = Math.max(ratioWidth,
                                  String.format("%.3f", ratios[i]).length());
        }

        String format = String.format("%%-%ds %%%dd %%%d.3f%%n",
                                      nameWidth, millisWidth, ratioWidth);
        String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",
                                            nameWidth, millisWidth, ratioWidth);
        System.out.printf(headerFormat, "Method", "Millis", "Ratio");

        // Print out absolute and relative times, calibrated against first job
        for (int i = 0; i < size; i++)
            System.out.printf(format, jobs.get(i).name(), milliss[i], ratios[i]);
    }

    private static String keywordValue(String[] args, String keyword) {
        for (String arg : args)
            if (arg.startsWith(keyword))
                return arg.substring(keyword.length() + 1);
        return null;
    }

    private static int intArg(String[] args, String keyword, int defaultValue) {
        String val = keywordValue(args, keyword);
        return (val == null) ? defaultValue : Integer.parseInt(val);
    }

    private static double doubleArg(String[] args, String keyword, double defaultValue) {
        String val = keywordValue(args, keyword);
        return (val == null) ? defaultValue : Double.parseDouble(val);
    }

    private static Pattern patternArg(String[] args, String keyword) {
        String val = keywordValue(args, keyword);
        return (val == null) ? null : Pattern.compile(val);
    }

    private static boolean booleanArg(String[] args, String keyword) {
        String val = keywordValue(args, keyword);
        if (val == null || val.equals("false")) return false;
        if (val.equals("true")) return true;
        throw new IllegalArgumentException(val);
    }

    private static List<Job> filter(Pattern filter, List<Job> jobs) {
        return (filter == null) ? jobs
            : jobs.stream()
            .filter(job -> filter.matcher(job.name()).find())
            .collect(toList());
    }

    private static void deoptimize(int sum) {
        if (sum == 42)
            System.out.println("the answer");
    }

    private static <T> List<T> asSubList(List<T> list) {
        return list.subList(0, list.size());
    }

    private static <T> Iterable<T> backwards(final List<T> list) {
        return new Iterable<T>() {
            public Iterator<T> iterator() {
                return new Iterator<T>() {
                    final ListIterator<T> it = list.listIterator(list.size());
                    public boolean hasNext() { return it.hasPrevious(); }
                    public T next()          { return it.previous(); }
                    public void remove()     {        it.remove(); }};}};
    }

    // Checks for correctness *and* prevents loop optimizations
    static class Check {
        private int sum;
        public void sum(int sum) {
            if (this.sum == 0)
                this.sum = sum;
            if (this.sum != sum)
                throw new AssertionError("Sum mismatch");
        }
    }
    volatile Check check = new Check();

    public static void main(String[] args) throws Throwable {
        new IteratorMicroBenchmark(args).run();
    }

    void run() throws Throwable {
//         System.out.printf(
//             "iterations=%d size=%d, warmup=%1g, filter=\"%s\"%n",
//             iterations, size, warmupSeconds, filter);

        final ArrayList<Integer> al = new ArrayList<>(size);

        // Populate collections with random data
        final ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (int i = 0; i < size; i++)
            al.add(rnd.nextInt(size));

        final ArrayDeque<Integer> ad = new ArrayDeque<>(al);
        final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<>(al.size());
        abq.addAll(al);

        // shuffle circular array elements so they wrap
        for (int i = 0, n = rnd.nextInt(size); i < n; i++) {
            ad.addLast(ad.removeFirst());
            abq.add(abq.remove());
        }

        ArrayList<Job> jobs = new ArrayList<>();

        List.<Collection<Integer>>of(
            al, ad, abq,
            new LinkedList<>(al),
            new PriorityQueue<>(al),
            new Vector<>(al),
            new ConcurrentLinkedQueue<>(al),
            new ConcurrentLinkedDeque<>(al),
            new LinkedBlockingQueue<>(al),
            new LinkedBlockingDeque<>(al),
            new LinkedTransferQueue<>(al),
            new PriorityBlockingQueue<>(al)).forEach(
                x -> {
                    jobs.addAll(collectionJobs(x));
                    if (x instanceof Deque)
                        jobs.addAll(dequeJobs((Deque<Integer>)x));
                });

        if (reverse) Collections.reverse(jobs);
        if (shuffle) Collections.shuffle(jobs);

        time(filter(filter, jobs));
    }

    List<Job> collectionJobs(Collection<Integer> x) {
        String klazz = x.getClass().getSimpleName();
        return List.of(
            new Job(klazz + " iterate for loop") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        int sum = 0;
                        for (Integer n : x)
                            sum += n;
                        check.sum(sum);}}},
            new Job(klazz + " iterator().forEachRemaining()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.iterator().forEachRemaining(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " spliterator().tryAdvance()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        Spliterator<Integer> spliterator = x.spliterator();
                        do {} while (spliterator.tryAdvance(n -> sum[0] += n));
                        check.sum(sum[0]);}}},
            new Job(klazz + " spliterator().forEachRemaining()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.spliterator().forEachRemaining(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " removeIf") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.removeIf(n -> { sum[0] += n; return false; }))
                            throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " contains") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object y = new Object() {
                        public boolean equals(Object z) {
                            sum[0] += (int) z; return false; }};
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.contains(y)) throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " remove(Object)") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    Object y = new Object() {
                        public boolean equals(Object z) {
                            sum[0] += (int) z; return false; }};
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        if (x.remove(y)) throw new AssertionError();
                        check.sum(sum[0]);}}},
            new Job(klazz + " forEach") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.forEach(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " toArray()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Object o : x.toArray())
                            sum[0] += (Integer) o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " toArray(a)") {
                public void work() throws Throwable {
                    Integer[] a = new Integer[x.size()];
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.toArray(a);
                        for (Object o : a)
                            sum[0] += (Integer) o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " toArray(empty)") {
                public void work() throws Throwable {
                    Integer[] empty = new Integer[0];
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Integer o : x.toArray(empty))
                            sum[0] += o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " stream().forEach") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.stream().forEach(n -> sum[0] += n);
                        check.sum(sum[0]);}}},
            new Job(klazz + " stream().mapToInt") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.stream().mapToInt(e -> e).sum());}}},
            new Job(klazz + " stream().collect") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.stream()
                                  .collect(summingInt(e -> e)));}}},
            new Job(klazz + " stream()::iterator") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Integer o : (Iterable<Integer>) x.stream()::iterator)
                            sum[0] += o;
                        check.sum(sum[0]);}}},
            new Job(klazz + " parallelStream().forEach") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        LongAdder sum = new LongAdder();
                        x.parallelStream().forEach(n -> sum.add(n));
                        check.sum((int) sum.sum());}}},
            new Job(klazz + " parallelStream().mapToInt") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
            new Job(klazz + " parallelStream().collect") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        check.sum(x.parallelStream()
                                  .collect(summingInt(e -> e)));}}},
            new Job(klazz + " parallelStream()::iterator") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
                            sum[0] += o;
                        check.sum(sum[0]);}}});
    }

    List<Job> dequeJobs(Deque<Integer> x) {
        String klazz = x.getClass().getSimpleName();
        return List.of(
            new Job(klazz + " descendingIterator() loop") {
                public void work() throws Throwable {
                    for (int i = 0; i < iterations; i++) {
                        int sum = 0;
                        Iterator<Integer> it = x.descendingIterator();
                        while (it.hasNext())
                            sum += it.next();
                        check.sum(sum);}}},
            new Job(klazz + " descendingIterator().forEachRemaining()") {
                public void work() throws Throwable {
                    int[] sum = new int[1];
                    for (int i = 0; i < iterations; i++) {
                        sum[0] = 0;
                        x.descendingIterator().forEachRemaining(n -> sum[0] += n);
                        check.sum(sum[0]);}}});
    }
}
Revision:	1.29
Committed:	Sun Jan 7 21:11:41 2018 UTC (6 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.28:	+0 -1 lines
Log Message:	remove unused import
#	Content
1	/*
2	* Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4	*
5	* This code is free software; you can redistribute it and/or modify it
6	* under the terms of the GNU General Public License version 2 only, as
7	* published by the Free Software Foundation.
8	*
9	* This code is distributed in the hope that it will be useful, but WITHOUT
10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12	* version 2 for more details (a copy is included in the LICENSE file that
13	* accompanied this code).
14	*
15	* You should have received a copy of the GNU General Public License version
16	* 2 along with this work; if not, write to the Free Software Foundation,
17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18	*
19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20	* or visit www.oracle.com if you need additional information or have any
21	* questions.
22	*/
23
24	/*
25	* @test
26	* @summary micro-benchmark correctness mode
27	* @run main IteratorMicroBenchmark iterations=1 size=8 warmup=0
28	*/
29
30	import static java.util.stream.Collectors.summingInt;
31	import static java.util.stream.Collectors.toList;
32
33	import java.lang.ref.WeakReference;
34	import java.util.ArrayDeque;
35	import java.util.ArrayList;
36	import java.util.Collection;
37	import java.util.Collections;
38	import java.util.Deque;
39	import java.util.Iterator;
40	import java.util.LinkedList;
41	import java.util.List;
42	import java.util.ListIterator;
43	import java.util.PriorityQueue;
44	import java.util.Spliterator;
45	import java.util.Vector;
46	import java.util.concurrent.ArrayBlockingQueue;
47	import java.util.concurrent.ConcurrentLinkedDeque;
48	import java.util.concurrent.ConcurrentLinkedQueue;
49	import java.util.concurrent.LinkedBlockingDeque;
50	import java.util.concurrent.LinkedBlockingQueue;
51	import java.util.concurrent.LinkedTransferQueue;
52	import java.util.concurrent.PriorityBlockingQueue;
53	import java.util.concurrent.CountDownLatch;
54	import java.util.concurrent.ThreadLocalRandom;
55	import java.util.concurrent.TimeUnit;
56	import java.util.concurrent.atomic.LongAdder;
57	import java.util.regex.Pattern;
58
59	/**
60	* Usage: [iterations=N] [size=N] [filter=REGEXP] [warmup=SECONDS]
61	*
62	* To run this in micro-benchmark mode, simply run as a normal java program.
63	* Be patient; this program runs for a very long time.
64	* For faster runs, restrict execution using command line args.
65	*
66	* This is an interface based version of ArrayList/IteratorMicroBenchmark
67	*
68	* @author Martin Buchholz
69	*/
70	public class IteratorMicroBenchmark {
71	abstract static class Job {
72	private final String name;
73	public Job(String name) { this.name = name; }
74	public String name() { return name; }
75	public abstract void work() throws Throwable;
76	}
77
78	final int iterations;
79	final int size; // number of elements in collections
80	final double warmupSeconds;
81	final long warmupNanos;
82	final Pattern filter; // select subset of Jobs to run
83	final boolean reverse; // reverse order of Jobs
84	final boolean shuffle; // randomize order of Jobs
85
86	IteratorMicroBenchmark(String[] args) {
87	iterations = intArg(args, "iterations", 10_000);
88	size = intArg(args, "size", 1000);
89	warmupSeconds = doubleArg(args, "warmup", 7.0);
90	filter = patternArg(args, "filter");
91	reverse = booleanArg(args, "reverse");
92	shuffle = booleanArg(args, "shuffle");
93
94	warmupNanos = (long) (warmupSeconds * (1000L * 1000L * 1000L));
95	}
96
97	// --------------- GC finalization infrastructure ---------------
98
99	/** No guarantees, but effective in practice. */
100	static void forceFullGc() {
101	CountDownLatch finalizeDone = new CountDownLatch(1);
102	WeakReference<?> ref = new WeakReference<Object>(new Object() {
103	protected void finalize() { finalizeDone.countDown(); }});
104	try {
105	for (int i = 0; i < 10; i++) {
106	System.gc();
107	if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
108	System.runFinalization(); // try to pick up stragglers
109	return;
110	}
111	}
112	} catch (InterruptedException unexpected) {
113	throw new AssertionError("unexpected InterruptedException");
114	}
115	throw new AssertionError("failed to do a \"full\" gc");
116	}
117
118	/**
119	* Runs each job for long enough that all the runtime compilers
120	* have had plenty of time to warm up, i.e. get around to
121	* compiling everything worth compiling.
122	* Returns array of average times per job per run.
123	*/
124	long[] time0(List<Job> jobs) throws Throwable {
125	final int size = jobs.size();
126	long[] nanoss = new long[size];
127	for (int i = 0; i < size; i++) {
128	if (warmupNanos > 0) forceFullGc();
129	Job job = jobs.get(i);
130	long totalTime;
131	int runs = 0;
132	long startTime = System.nanoTime();
133	do { job.work(); runs++; }
134	while ((totalTime = System.nanoTime() - startTime) < warmupNanos);
135	nanoss[i] = totalTime/runs;
136	}
137	return nanoss;
138	}
139
140	void time(List<Job> jobs) throws Throwable {
141	if (warmupNanos > 0) time0(jobs); // Warm up run
142	final int size = jobs.size();
143	final long[] nanoss = time0(jobs); // Real timing run
144	final long[] milliss = new long[size];
145	final double[] ratios = new double[size];
146
147	final String nameHeader = "Method";
148	final String millisHeader = "Millis";
149	final String ratioHeader = "Ratio";
150
151	int nameWidth = nameHeader.length();
152	int millisWidth = millisHeader.length();
153	int ratioWidth = ratioHeader.length();
154
155	for (int i = 0; i < size; i++) {
156	nameWidth = Math.max(nameWidth, jobs.get(i).name().length());
157
158	milliss[i] = nanoss[i]/(1000L * 1000L);
159	millisWidth = Math.max(millisWidth,
160	String.format("%d", milliss[i]).length());
161
162	ratios[i] = (double) nanoss[i] / (double) nanoss[0];
163	ratioWidth = Math.max(ratioWidth,
164	String.format("%.3f", ratios[i]).length());
165	}
166
167	String format = String.format("%%-%ds %%%dd %%%d.3f%%n",
168	nameWidth, millisWidth, ratioWidth);
169	String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",
170	nameWidth, millisWidth, ratioWidth);
171	System.out.printf(headerFormat, "Method", "Millis", "Ratio");
172
173	// Print out absolute and relative times, calibrated against first job
174	for (int i = 0; i < size; i++)
175	System.out.printf(format, jobs.get(i).name(), milliss[i], ratios[i]);
176	}
177
178	private static String keywordValue(String[] args, String keyword) {
179	for (String arg : args)
180	if (arg.startsWith(keyword))
181	return arg.substring(keyword.length() + 1);
182	return null;
183	}
184
185	private static int intArg(String[] args, String keyword, int defaultValue) {
186	String val = keywordValue(args, keyword);
187	return (val == null) ? defaultValue : Integer.parseInt(val);
188	}
189
190	private static double doubleArg(String[] args, String keyword, double defaultValue) {
191	String val = keywordValue(args, keyword);
192	return (val == null) ? defaultValue : Double.parseDouble(val);
193	}
194
195	private static Pattern patternArg(String[] args, String keyword) {
196	String val = keywordValue(args, keyword);
197	return (val == null) ? null : Pattern.compile(val);
198	}
199
200	private static boolean booleanArg(String[] args, String keyword) {
201	String val = keywordValue(args, keyword);
202	if (val == null \|\| val.equals("false")) return false;
203	if (val.equals("true")) return true;
204	throw new IllegalArgumentException(val);
205	}
206
207	private static List<Job> filter(Pattern filter, List<Job> jobs) {
208	return (filter == null) ? jobs
209	: jobs.stream()
210	.filter(job -> filter.matcher(job.name()).find())
211	.collect(toList());
212	}
213
214	private static void deoptimize(int sum) {
215	if (sum == 42)
216	System.out.println("the answer");
217	}
218
219	private static <T> List<T> asSubList(List<T> list) {
220	return list.subList(0, list.size());
221	}
222
223	private static <T> Iterable<T> backwards(final List<T> list) {
224	return new Iterable<T>() {
225	public Iterator<T> iterator() {
226	return new Iterator<T>() {
227	final ListIterator<T> it = list.listIterator(list.size());
228	public boolean hasNext() { return it.hasPrevious(); }
229	public T next() { return it.previous(); }
230	public void remove() { it.remove(); }};}};
231	}
232
233	// Checks for correctness and prevents loop optimizations
234	static class Check {
235	private int sum;
236	public void sum(int sum) {
237	if (this.sum == 0)
238	this.sum = sum;
239	if (this.sum != sum)
240	throw new AssertionError("Sum mismatch");
241	}
242	}
243	volatile Check check = new Check();
244
245	public static void main(String[] args) throws Throwable {
246	new IteratorMicroBenchmark(args).run();
247	}
248
249	void run() throws Throwable {
250	// System.out.printf(
251	// "iterations=%d size=%d, warmup=%1g, filter=\"%s\"%n",
252	// iterations, size, warmupSeconds, filter);
253
254	final ArrayList<Integer> al = new ArrayList<>(size);
255
256	// Populate collections with random data
257	final ThreadLocalRandom rnd = ThreadLocalRandom.current();
258	for (int i = 0; i < size; i++)
259	al.add(rnd.nextInt(size));
260
261	final ArrayDeque<Integer> ad = new ArrayDeque<>(al);
262	final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<>(al.size());
263	abq.addAll(al);
264
265	// shuffle circular array elements so they wrap
266	for (int i = 0, n = rnd.nextInt(size); i < n; i++) {
267	ad.addLast(ad.removeFirst());
268	abq.add(abq.remove());
269	}
270
271	ArrayList<Job> jobs = new ArrayList<>();
272
273	List.<Collection<Integer>>of(
274	al, ad, abq,
275	new LinkedList<>(al),
276	new PriorityQueue<>(al),
277	new Vector<>(al),
278	new ConcurrentLinkedQueue<>(al),
279	new ConcurrentLinkedDeque<>(al),
280	new LinkedBlockingQueue<>(al),
281	new LinkedBlockingDeque<>(al),
282	new LinkedTransferQueue<>(al),
283	new PriorityBlockingQueue<>(al)).forEach(
284	x -> {
285	jobs.addAll(collectionJobs(x));
286	if (x instanceof Deque)
287	jobs.addAll(dequeJobs((Deque<Integer>)x));
288	});
289
290	if (reverse) Collections.reverse(jobs);
291	if (shuffle) Collections.shuffle(jobs);
292
293	time(filter(filter, jobs));
294	}
295
296	List<Job> collectionJobs(Collection<Integer> x) {
297	String klazz = x.getClass().getSimpleName();
298	return List.of(
299	new Job(klazz + " iterate for loop") {
300	public void work() throws Throwable {
301	for (int i = 0; i < iterations; i++) {
302	int sum = 0;
303	for (Integer n : x)
304	sum += n;
305	check.sum(sum);}}},
306	new Job(klazz + " iterator().forEachRemaining()") {
307	public void work() throws Throwable {
308	int[] sum = new int[1];
309	for (int i = 0; i < iterations; i++) {
310	sum[0] = 0;
311	x.iterator().forEachRemaining(n -> sum[0] += n);
312	check.sum(sum[0]);}}},
313	new Job(klazz + " spliterator().tryAdvance()") {
314	public void work() throws Throwable {
315	int[] sum = new int[1];
316	for (int i = 0; i < iterations; i++) {
317	sum[0] = 0;
318	Spliterator<Integer> spliterator = x.spliterator();
319	do {} while (spliterator.tryAdvance(n -> sum[0] += n));
320	check.sum(sum[0]);}}},
321	new Job(klazz + " spliterator().forEachRemaining()") {
322	public void work() throws Throwable {
323	int[] sum = new int[1];
324	for (int i = 0; i < iterations; i++) {
325	sum[0] = 0;
326	x.spliterator().forEachRemaining(n -> sum[0] += n);
327	check.sum(sum[0]);}}},
328	new Job(klazz + " removeIf") {
329	public void work() throws Throwable {
330	int[] sum = new int[1];
331	for (int i = 0; i < iterations; i++) {
332	sum[0] = 0;
333	if (x.removeIf(n -> { sum[0] += n; return false; }))
334	throw new AssertionError();
335	check.sum(sum[0]);}}},
336	new Job(klazz + " contains") {
337	public void work() throws Throwable {
338	int[] sum = new int[1];
339	Object y = new Object() {
340	public boolean equals(Object z) {
341	sum[0] += (int) z; return false; }};
342	for (int i = 0; i < iterations; i++) {
343	sum[0] = 0;
344	if (x.contains(y)) throw new AssertionError();
345	check.sum(sum[0]);}}},
346	new Job(klazz + " remove(Object)") {
347	public void work() throws Throwable {
348	int[] sum = new int[1];
349	Object y = new Object() {
350	public boolean equals(Object z) {
351	sum[0] += (int) z; return false; }};
352	for (int i = 0; i < iterations; i++) {
353	sum[0] = 0;
354	if (x.remove(y)) throw new AssertionError();
355	check.sum(sum[0]);}}},
356	new Job(klazz + " forEach") {
357	public void work() throws Throwable {
358	int[] sum = new int[1];
359	for (int i = 0; i < iterations; i++) {
360	sum[0] = 0;
361	x.forEach(n -> sum[0] += n);
362	check.sum(sum[0]);}}},
363	new Job(klazz + " toArray()") {
364	public void work() throws Throwable {
365	int[] sum = new int[1];
366	for (int i = 0; i < iterations; i++) {
367	sum[0] = 0;
368	for (Object o : x.toArray())
369	sum[0] += (Integer) o;
370	check.sum(sum[0]);}}},
371	new Job(klazz + " toArray(a)") {
372	public void work() throws Throwable {
373	Integer[] a = new Integer[x.size()];
374	int[] sum = new int[1];
375	for (int i = 0; i < iterations; i++) {
376	sum[0] = 0;
377	x.toArray(a);
378	for (Object o : a)
379	sum[0] += (Integer) o;
380	check.sum(sum[0]);}}},
381	new Job(klazz + " toArray(empty)") {
382	public void work() throws Throwable {
383	Integer[] empty = new Integer[0];
384	int[] sum = new int[1];
385	for (int i = 0; i < iterations; i++) {
386	sum[0] = 0;
387	for (Integer o : x.toArray(empty))
388	sum[0] += o;
389	check.sum(sum[0]);}}},
390	new Job(klazz + " stream().forEach") {
391	public void work() throws Throwable {
392	int[] sum = new int[1];
393	for (int i = 0; i < iterations; i++) {
394	sum[0] = 0;
395	x.stream().forEach(n -> sum[0] += n);
396	check.sum(sum[0]);}}},
397	new Job(klazz + " stream().mapToInt") {
398	public void work() throws Throwable {
399	for (int i = 0; i < iterations; i++) {
400	check.sum(x.stream().mapToInt(e -> e).sum());}}},
401	new Job(klazz + " stream().collect") {
402	public void work() throws Throwable {
403	for (int i = 0; i < iterations; i++) {
404	check.sum(x.stream()
405	.collect(summingInt(e -> e)));}}},
406	new Job(klazz + " stream()::iterator") {
407	public void work() throws Throwable {
408	int[] sum = new int[1];
409	for (int i = 0; i < iterations; i++) {
410	sum[0] = 0;
411	for (Integer o : (Iterable<Integer>) x.stream()::iterator)
412	sum[0] += o;
413	check.sum(sum[0]);}}},
414	new Job(klazz + " parallelStream().forEach") {
415	public void work() throws Throwable {
416	for (int i = 0; i < iterations; i++) {
417	LongAdder sum = new LongAdder();
418	x.parallelStream().forEach(n -> sum.add(n));
419	check.sum((int) sum.sum());}}},
420	new Job(klazz + " parallelStream().mapToInt") {
421	public void work() throws Throwable {
422	for (int i = 0; i < iterations; i++) {
423	check.sum(x.parallelStream().mapToInt(e -> e).sum());}}},
424	new Job(klazz + " parallelStream().collect") {
425	public void work() throws Throwable {
426	for (int i = 0; i < iterations; i++) {
427	check.sum(x.parallelStream()
428	.collect(summingInt(e -> e)));}}},
429	new Job(klazz + " parallelStream()::iterator") {
430	public void work() throws Throwable {
431	int[] sum = new int[1];
432	for (int i = 0; i < iterations; i++) {
433	sum[0] = 0;
434	for (Integer o : (Iterable<Integer>) x.parallelStream()::iterator)
435	sum[0] += o;
436	check.sum(sum[0]);}}});
437	}
438
439	List<Job> dequeJobs(Deque<Integer> x) {
440	String klazz = x.getClass().getSimpleName();
441	return List.of(
442	new Job(klazz + " descendingIterator() loop") {
443	public void work() throws Throwable {
444	for (int i = 0; i < iterations; i++) {
445	int sum = 0;
446	Iterator<Integer> it = x.descendingIterator();
447	while (it.hasNext())
448	sum += it.next();
449	check.sum(sum);}}},
450	new Job(klazz + " descendingIterator().forEachRemaining()") {
451	public void work() throws Throwable {
452	int[] sum = new int[1];
453	for (int i = 0; i < iterations; i++) {
454	sum[0] = 0;
455	x.descendingIterator().forEachRemaining(n -> sum[0] += n);
456	check.sum(sum[0]);}}});
457	}
458	}